The present invention is related to an improved numeral lock housing structure in which the numeral wheel window is re-designed and formed between the lateral face and front face of the lock housing. The numeral wheel window extends into the front face without crossing the mating edge thereof. Therefore, the mating edges of the two halves of the lock housing will not be slotted so that the structure of the front face of the lock housing is kept integrated. In addition, the numeral wheel is positioned in the corner between the lateral face and front face so that the numeral wheel has larger turning angle each time the numeral wheel is turned.
FIG. 1 shows a conventional numeral lock. Several numeral wheel windows 13 are formed on a lateral face 12 of the lock housing 11. Several numeral wheels 10 are disposed in the windows 13. The mating edges 15 of the front faces of the lock housing 11 are not interrupted by the windows 13. Therefore, the front faces of the lock housing 11 is integrated and is not subject to damage of alien article or external force. However, the numeral wheels 10 are presented only on single lateral face of the lock housing 11. Therefore, the numeral wheel has greatly limited turning angle each time the numeral wheel is turned. As a result, it is necessary to many times turn the numeral wheel for unlocking the numeral lock. This is quite inconvenient. 
FIG. 2 shows another type of conventional numeral lock. The numeral wheels 10 are directly bridged over the front face 16 of the lock housing 11 between two lateral faces 12 thereof. Therefore, the mating edges 15 of the lock housing 11 are interrupted. Accordingly, the structural strength of the lock housing 11 is weakened. Also, an alien piece can be easily extended into the lock housing 11 to damage the same. In addition, the numeral wheels 10 are apt to be collided and damaged. As a result, the strength and reliability of the numeral lock as a whole are poor. However, the numeral wheel 10 has larger turning angle each time the numeral wheel 10 is turned so that the operation of the numeral lock is facilitated.
FIG. 3 shows still another type of conventional numeral lock. Several numeral wheel windows 17 are formed on the front face 14 of the lock housing 11 corresponding to the numeral wheels 10. Such numeral wheel windows 17 facilitate identification of the unlocking number of the numeral wheels 10. However, the mating edges 15 of the lock housing 11 are interrupted and the structural strength of the lock housing 11 is weakened. In addition, the numeral wheel 10 has small turning angle each time the numeral wheel 10 is turned.